To make clear the mechanisms of liquid penetration of wood, it is tested for the various pretreated samples of Hinoki, Sugi and Beimatu (ex. extraction in the hot water and the precompressive treatment and so on), and the liquid movement are observated by the CCD camera system on the reflecting optical microscope.Results obtained are as follow :1)The liquid penetration of Hinoki wood become to be translated by the diffuse wetting.2)The liquid penetration into the tracheid is acted by the repetition of the progress and the stoppage.3)The rate of the liquid movement into the tracheid under the aspiration occurs remarkably change in the range from the force of 10kg/cm^2 to 20kg/cm^2.